1. Field of the Invention
The present invention relates to a system method for reading an electronic tag such as an RFID, etc., and more particularly, to a disk tag reading device for reading contents of a tag attached to a disk such as a CD, a DVD, etc.
2. Description of the Related Art
In recent years, attention has been paid to an RFID (Radio Frequency Identification) system as a system for managing parts or an inventory. For example, if the production or distribution of CDs, DVDs, etc., tags of as many stacked CDs or DVDs as possible must be collectively read. However, if many CDs or DVDs are stacked, there is a problem that the number of readable CDs or DVDs is reduced due to an influence of a recording medium (metal portion) of a CD or a DVD.
FIG. 1 explains a CD to which a tag is attached. The tag 100 is attached to the proximity of the center of the CD, and a recording medium (metal portion) 101 exists outside the tag.
FIG. 2 explains a conventional example of a reading system, for example, in a case where many CDs are stacked. In this figure, a method for reading contents of a tag by connecting a high-gain antenna 107 to an RFID reader/writer system 106, and by making the antenna 107 close to the CD is used if contents of tags are read from many CDs to which RFID tags are attached. This method, however, has a problem that the number of CDs from which data of tags can be accurately read becomes small among the stacked many CDs as described above.
The following documents exist as conventional techniques for such a system for reading a tag, etc.
[Patent Document 1] Japanese Patent Publication No. 2001-357366 “Antenna Device and Reader/Writer Device”
[Patent Document 2] Japanese Patent Publication No. 2003-69549 “Information Protection Management System Using a Recording Medium Equipped with an RFID”
Patent Document 1 discloses a technique, for example, using a pillar-shaped of coiled insulator based material antenna having a height direction that is an insertion direction into a cylinder in order to communicate with a non-contact data carrier installed on the inner surface of the cylinder.
Patent Document 2 discloses an information protection management system for recording a decryption key to an RFID chip of a recording medium on which encrypted information is recorded, and for decrypting the encrypted information by using the decryption key read from the RFID chip when the encrypted information is read from the medium.
These techniques, however, cannot solve the problem that contents of tags attached to disks cannot be accurately read when many disks such as CDs, DVDs, etc. are stacked.